• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.151-160
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• 2008

In this paper, the analysis results of synthetic resonance characteristics are described for the electrohydraulic thrust vector control actuation system. The synthetic resonance is induced by integration of position servo actuation system on the flexible launch vehicle mounting structure. The new resonance mode is synthesized due to composition of hydraulic resonance for electrohydraulic position servo system with inertia load condition and structural resonance for flexible mounting structure. This synthetic resonance can make stability of control system worse by feedback and amplification of control system. The exact nonlinear analysis model of this phenomenon is developed to predict and design a control algorithm for improvement characteristics. The DPF (Dynamic Pressure Feedback) control algorithm has been designed and has excellent resonance suppression capability.

• 기계와재료
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• v.25 no.3
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• pp.6-15
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• 2013

유압프레스의 단점을 극복하기 위해서 서보모트를 장착하여 성형속도를 높인 서보 유압프레스를 개발하게 되었으며, 특히나 서보모터를 국내산으로 적용하여 듀얼형으로 유압시스템의 효율성을 높여 최종적으로 개발함으로써 서보 유압프레스를 완전 국산화하였다. 또한 하사점 위치 제어의 용이성을 확보하기 위해 프레스 램용 메인 실린더에 톱니나사부를 만들어 임의의 위치에 정지할 수 있는 정지정도 및 하사점 위치 제어정밀도를 향상시켰으며, 유량의 미세 제어를 통해 프레스 램의 동작성을 개선코자 하였다. 다이쿠션은 메인 실린더와의 연계 제어를 통해 제품의 손상 방지 및 제품 추출의 용이성을 확보하였으며, 소재의 종류나 제품의 형상 특성에 따라 프리모션 제어가 가능한 지식기반형 자율제어 시스템을 적용하였다. 듀얼 서보시스템과 유압펌프가 연계구동함에 따라 기존 유압프레스 보다 약 40%이상의 에너지절감을 달성할 수 있을 것으로 예측되며, 현재 에코머신 인증제도에 대한 논의가 활발한 시점에서 매우 적합하고 필요한 하이브리드형 서보 유압프레스의 국산화 개발 사례라고 하겠다.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.168-173
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• 2004

This article describes the design of a hydraulic system for a power split type continuously variable transmission (CVT). The CVT considered here, is composed of planetary gears, clutches, and a torque converter which is mainly used for the realization of CVT function. Similar to automatic transmissions, the hydraulic system of CVT is designed for supplying hydraulic flows and pressures to each component of CVT, in order to activate the clutch engagements and torque converter operation, and to cool the drivetrain. By using the mathematical models of drivetrain, a simulation program was developed to investigate the power performance of CVT equipped vehicle and the operating conditions of each component of CVT. And the design parameters of the hydraulic system and clutches were calculated using the operating conditions and power requirements which obtained from the simulation results. Finally the hydraulic circuit design of prototyped valve body is presented based on the numerical results of this analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.9-17
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• 2019

Variable guide vanes(VGVs) that consist of link mechanisms and an actuator system are required for an aircraft gas turbine engine to adjust the incidence angle of stator vanes. In this study, we developed a VGV actuator system for three-stage VGVs with two hydraulic actuators. The requirements for the actuator system were derived by analyzing the link mechanisms and air loads, and a hydraulic power-pack was developed based on these requirements. Through a load test using the actuator test-rig and the application of synchronizing control logic with proper control gains, the actuator system could be developed and verified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.335-340
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• 1992

유압 시스템(System)은 원동기의 기계적 에너지를 유압펌프가 작동유를 압력 에너지의 형태로변환 시켜 이것을 유합 실린더(Cylinder)등의 엑츄에이터(Actuator)가 다시 기계적 에너지로 변환시켜 부하 를 구동하게한다. 상용차(NT-1, KH 등)용 파워스티어링(Power Steering)에 장착되는 Vane Type Oil Pump (이하 VOP)가 바로 이와같은 역할을 담당하고 있다. 본 연구에서는 VOP의 성능과 관련되어지는 주요 제원(Parameter)인 미끄럼부에서의 틈새, 작동유점도, 압력변화, 회전수 등을 다양하게 변화시키는 모의실험(Simulation)을 통하여각각의 조건하에서얻어지는 누설 유량과 체적효율을 수치적 으로 예측하고 이것을 주요제원을 고려하여 해석해서 정량적인 값을 얻는 것을 목적으로한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.349-357
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• 2017

If an actuation system of the tactical missile is required very fast response time on conditions of short operating time and big loads on the actuator, we would prefer to adopt a small hydraulic system. In this paper, a mathematical model is proposed to analyze and simulate the small hydraulic actuation system. The mathematical model consists of a high pressure vessel model, a pressure regulator model, a hydraulic reservoir model and a actuator model. The suggested model is validated by comparison of simulation results with experimental data. The simulation results show that the mathematical model could be useful for designing a hydraulic actuation system.

• Journal of Drive and Control
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• v.11 no.2
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• pp.9-15
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• 2014

This paper deals with the issue of force synchronizing control for the clamping servomechanism of injection molding machines. Prior to the controller design, a virtual design model has been developed for the clamping mechanism with hydraulic systems. Then, a synchronizing controller is designed and combined with an adaptive feedforward control in order to accommodate the mismatches between the real plant and the linear model plant used. As a disturbance, the leakage due to the ring gap with relative motion in the cylinder has been introduced. From the robust force tracking simulations, it is shown that a significant reduction in the force synchronizing error is achieved through the use of a proposed control scheme.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.303-304
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.184-184
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• 2004

볼 나사는 반도체ㆍLCDㆍPDP 등 전자제품 조립장비 제조업체와 CNC 공작기계, 정밀측정기계, 직교좌표로봇, 반송장치, 항공기용 유압구동장치 대체품, 전동공구, 파워 steering, 테이블 개폐장치 등에서 구동 장치 및 물품의 이송을 위해 대부분 사용되는 중요한 기계요소 중의 하나이다. 그것은 회전운동을 직선운동으로 전환해주는 기구부에 들어가는 가장 중요한 부품이며, 원통형의 봉에 나선형의 그루브를 가공한 장축의 나사와 단축의 너트 사이에 볼을 게재시켜 축의 회전 시 적은 구름마찰로 인해, 너트부가 직선 운동하는데 원활 하게 만들어진 기계요소이다.(중략)

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.963-970
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• 2015

In this study, the pressurization characteristics of the small piezoelectric hydraulic pump for a brake system has been analyzed through modeling the full hydraulic pump components; the pump chamber, check valve, pump load, pump drive controller etc. To analyze the pressurization characteristics, the process of charging pressure in the chamber with stacked-layer piezoelectric actuator were firstly modeled. Secondly, the flow coefficient of the check valve in terms of valve opening has been calculated after computational fluid dynamics analysis, such as the pressure distribution around check valve and the flow rate, was conducted. Also the pump driving controller, which controls the input voltage to the actuator, was designed to make the load pressure follow the input pressure command. The simulation results find that it takes about 0.03ms to reach the operating load pressure required for the braking system. The simulation result was also verified through comparison to the result of the pump performance test.